Apparatus for the conversion of motion of one type into motion of another type



A. BARR AND w. snoun.

`PPARATUS FOR THE CONVERSION 0F MOTION 0F ONE TYPE INTO MOTION OFANOTHER TYPE.

APPLICATION FILED MIG. I5, I9I8.

1,339,643 v Paten (1M 11,1920. /mF/f///,f f f6/@fw 6%- f4/f I L r s El 'UNITED STATES PATENT OFFICE.,

ARCHIBALD BARR AND WILLIAM STROUD, OF GLASGOW, SCOTLAND, ASSIGNORS T0BARR AND STRO'UD LIMITED, OF ANNIESLAND, GLASGOW, SCOTLAND.

APPARATUS FOR THE CONVERSION :0F MOTION OF ONE TYPE INTO MOTION 'iO-FANOTHER TYPE.

Specficationof Letters Patent.

Patented May ,11, 1920.

Application filed August 15, 1918. Serial No. 250,087.

To all whom t may concer/t Be it known tha't we, ARCHIBALD BARR andIILLIAM S'rRoUD, subjects of the 'King of Great Britain and Ireland, andboth of CaXton street, Anniesland, Glasgow, Scotland, have invented new.and useful Improvements in Apparatus for the Conversion of Motion ofone Type into Motion of Another Type, of which the following is aspecification. A

The object of our invention is to provide improved means for theconversion of motion according to one law (or type) into motionaccording to another law l(or type). For example, it provides means forthe conversion of motions in accordance with those of the working Vheadof a .constant base rangefinder-which commonly follow the reciprocal lawwith reference to changes in range-into motions proportional Y Vto thechanges of range, t'. c., kthe conversion of motions according` to areciprocal scale into motions according to a uniform scale; or again,for the conversion of motions ,according to a uniform scale of rangesinto motions according to a logarithmic scale, or according to a scaleof gunsight elevations corresponding to the ranges; or for otheranalogous purposes.

Patents with the same lobject in view are well known, but in mechanismgenerally for effecting such conversions of motions a difficulty ariseswhen the velocity-ratio lvaries over wide limits at different parts ofthe conversion, c. g., to convert a reciprocal scale of ranges extendingfrom 3,000 to 30,000 yards into a uniform scale, with the velocity-ratiovarying from 1 to 100, in one stage, the size of the mechanismrequiredas at present known, for sufficient accuracy, would necessarily begreat. A method has been pro- .'icsed to effect conversions of thischaractery in two (or more) stages, each, say, of 1 to 10, whereby areduction in the vsize of the mechanism required is obtained.

Our present invention has for its object improvements in or connectedwith apparatus and the pro'ductionof improved apparatus for use in theconversion ofmotion according to one law (or type) into motion according-to another law (or type) in which the velocity-ratio may vary over widelimits (say, 1 to 100) at different parts of the conife'rsion, by meansof which apparatus the conversion inaybe'effected in one stage', and

the apparatus produced maybe of small dimensions .in comparison `withmechanisms generally known for such purposes. Moreover, a novel processof conversion is made possible with the use of apparatus according -tothis invention in which the velocityratio kmay be furnished, where @cdenotes the motion'applied to the apparatus, y the emergent motion andHm) is any function of m.

Apparatus according to this invention comprises three gear elementsconstituting a main differential gear with means for applying to thefirst and second elements forces tending to drive them in oppositesenses so far as their effects on the third element are concerned,associated with mechanism for controlling the ratio of the motionsimparted to the first and second'elements in a pre determinedprogressively variable manner, whereby, for example, the motion of thelfirst or the second element may be in accordance with the law A to beconverted and the motion of the third element in accordance with the lawB desired, or the motion of a part of mechanism provided 'for drivingthe first and second elements may be in accordance with the law A andthe motion of the third element in accordance with the law B.

Denoting the elements of an 'ordinary differential' gear by 1, 2, 3 inwhich 2 is the jockey element, 'it is clear that if the ,ele-

ments 1 and 3 are geared together in some suitable non-uniform way andprovision as small as desired by adopting suitable nonuniformcontrolling gear, in fact, .it may be made Zero by arranging that thevelocity of 1 is equal and opposite to that of 3. Further, thevelocityiatio of 2 may be'made negative compared with (say) 1, in thefollowing way If 1 is moved forward at a certain rate and 3 backward at'a Ysmaller rate, then we may regard 2 as moving Vforward .at a ratedepending on the differences of the rates of1 and 3. As soon as the rateof motion of 3 equals that of 1, 2 becomes stationary, while if thelrate 'of '3 exceeds that of 1, 2 will move backward. By our invention itis thus possible to make 2 move in any prescribed manner forward orbackward as may be desired. Further, in this way, if ae denotes themotion imparted to the mechanism and g/ the emergent motion it ispossible to obtain a mechanical solution of the equation yzf whateverthe form of this function.

Taking then, as an example, the case of the conversion of a reciprocalscale of ranges into a uniform scale, we may gear the jockey element 2of the differential gear to the working head of a rangefinder while weactually work by hand either the element 1 or 3. If then 1 and 3 begeared together in some suitable non-uniform way so that 3 moves in theopposite direction to 1, when, say, 1 is turned by hand, we may arrangethat each revolution of 1 shall correspond to a definite change ofrange.

In certain cases it is conceivable that there may be a considerableresistance to the motion of 2, in which case considerable forces willhave to be transmitted through the non-uniform gear between 1 and Thisobjection may be overcome by applying a direct drive to each of theelements 1 and 3. For instance, this may be done by providing asupplementary differential gear with an idle wheel, in which case a maindifferential gear 1, 2, 3 and a supplementary differential gear 11, 21,31 are employed, 2 and 21 being the jockeys, 1 being directly geared to11, and 3 being geared to 31 through an idle wheel. If now we apply adrive to 21 (according to a uniform scale) and obtain our drive to therangefinder from 2 by suitable non-uniform gearing be tween 1 and 3 (asbefore) we may arrange that the motions of 2 shall be according to therequired reciprocal scale. In ythis case 2Y moves in accordance with thedifference in the motions of 1 and 3 which are each directly driven, thenon-uniform gear between 1 and 3 being employed to regulate the relativemotions of 1 and In this way the force transmitted through thisnon-uniform gear is appreciably reduced.

In the use of differential gears as above described, we have assumedthat the drives are imparted to 1 and 3, and the part driven isconnected to the jockey element 2, but in all casesY as is well-known inconnection with differential gears) the drives may be imparted to anytwo of the three elements of the gear provided their effects on thethird element are in opposite senses, while the third element isconnected to the part to be driven. 4

Examples of construction according to this invention will now bedescribed with reference to the accompanying drawing, in which YFiguresl, 2 and 3 are diagrammatic plan views. Fig. 4 represents asection ofone form which the gear may take. Fig. 5 shows in' side view aportion of the gear, and Fig. 6 is a plan of a detail. V

In the drawing, 1, 2, 3 designate the elements of the main differentialgear, and 11,

11, 31 the elements of the supplementary differential gear.

In Fig. 1 force is applied to a handle 5 to which the spindle of jockey21 is hXed, thus the bevel wheels 11 vand 31 tend to turn in the samesense. Fixed to 11 and 31 respectively are gear wheels f5 and 7. Gearwheels S and 9 are fixed to bevel wheels 1 and 3 respectively while 8gears directly with G, and 9 (through an idle gear wheel el) with 7.Thus under the influence of the force applied to 5 the bevel wheels 1and 3 tend to turn in opposite senses so that the motion of jockey wheel2 (and shaft 10) is de- 1 and 3. VIn Fig. 1 there is no device shown forcontrolling the relative motions of 1 and 3. In Fig. 2, however,mechanism is indicated for controlling the relative motions of 1 and 3.Here wheel 8 gears with a wheel 141 to which a bevel wheel 11 is fixed.Bevel wheel 11 gears with a bevel 12 whose spindle is fixed, and bevel12 gears with a bevel 13 to which a toothed spiral 15 is fixed. Spiral15 gears with a complementary toothed spiral 17 fixed to wheel 9. Thetwo spirals 15 and 17 determine by their form the nature of the motionimparted to shaft 10. In the position shown in the figure spiral 17 willturn through a much large? angle than spiral 15, /ie., wheel 9 will willturn through a much larger angle than wheel 8 and consequently in theposition shown shaft 10 will turn in the same sense as wheel 9. Thisoccurs when the place of gearing 16 of the two spirals is nearer thespindle of9 than the spindle of 13. If the place of gearing 16 is,however, nearer the spindle of 13 than the spindle of 9 the shaft 10will turn in the same senseas wheel 8. Thus as shaft 5 is turned in onesense shaft 10 will move (say) forward then stop and will then moveback-ward.

In Fig. 1 (for which Fig. 3 is a diagrammatic representation) there isshown a section of the gear as applied (say) to the conversion ofthegreciprocal scale of a rangefinder into a uniform scale. In this caseas the handle 5 is turned in one sense the shaft 10 will likewise haveto move always in one sense, e., notbackward at one part and forward atanother part. The speed of the wheel 1 is in all circumstances greaterthan that of wheel 3 (andl their motions are in opposite directions) sothat the .speed of shaft 10 which depends on their difference in speednever falls to zero. InFig. t the shaft 10 is used as the bearing for atoothed .helicospiral member 2O sol thatrlO and 2O termined by thedifference in the motions of can rotate independently. Considering Fig.3, the functions of theparts 1, 2,3, 11, 21, 31,

` etc., with the exception :that Gand 8 are geared together lby 6gearing with a gear wheel 81 fixed to 8, correspond to those of similarparts in Fig. "2, Abut instead of the controlling mechanism consistingof the two spirals 15 and 17 of Fig. 2, we have two toothedhelico-spiral members 20 and y21 with an idle whee'l22 whose center iscapable of motion in two dimensions in the plane of the paper. If 'thetwo helico-spiral members 2O and 21 are correctly formed motions of themember 2() and the gears 9, 3, 4 and 7 all directly geared together areaccording to a uniform scale while motions of the shaft 10 may bearranged to be in accordance with a reciprocal scale, thus when idlewheel 22 is `gearing with the teeth on the large radius of'20 and withthe teeth on the small radius of 21 (as shown in Fig. 4) any motion `of7 which is lfixed to shaft 30 will producea relatively large `motion of21 and therefore of bevel wheel 1 geared to v21 through wheels 14 and 8and a relatively small motion of 2O and therefore of bevel wheel 3. Itwill vbe seen that 1 and 3 `move in opposite senses `so that ythe motionof 2 is determined by the motion of one vless that of 3. Vith the idlewheel 22 inthe position shown at Fig. 4 when handle 5 is turned shaft 10will rotate rapidly backward rela tive to 20. If, however, idle wheel 22Vis gearing with the teeth on the small vradius of 20 and with the teethon .the large radiusV of 21 then the condition will be reversed andshaft 10 will now rotate slowly while i 20 will be rapidly turned. Tfnow shaft 10 be geared to the working head of a range.- finder thenstarting from the position of the idle wheel 22 shown in Fig. 4, if wesuppose handle 5 to be uniformly turned, shaft 10 is movedV rapidly atthe start (corresponding to low ranges), it gradually gets slower andslower as idle wheel 22 moves vto the left 'in Fig. 4 and approachesshaft 1() until `when 22 is nearest shaft 10 this shaft will be slowlyrotating (corresponding to Y the highest range for which conversion isdesired). In Fig. 4 it will be seen that the convolutions on the left ofthe two helicospiral members are so arranged that the Vidle wheel 22first approaches shaft 10 and then rapidly vrecedes from it. This iswith the object of enabling the'operator to rap idly approach theinfinity position vof the i-nstrument.

Taking Fig. 4 in detail, wheel 7 is fixed to rotate with `shaft 3()whose right hand bearing is supported by `the shaft 31 to which handle 5is fixed. Wheel 7 gears through idle wheel'4 with wheel 9 which is fixedto the helicofspiral member. All the parts 7, 4, 9 and 20 move inaccordance with a uniform scale so that ifit is desired to transmit theindication of the :instrument to a distance in uniform steps it issuflicient to actuate a step-by-step transmitter by the sha-ft 30.

In order to suitably support the floating idle'wheel 22 between the twohelico-spiral members we may use the arrangement shown in Fig. 4. Inthis case the helico-spiral 2O is fixed axiallyand carries a wheel 33gear-y ing with an equal wheel 35 through .idle wheel 34. theel 35 isfixed to shaft -36 upon which there is cut a screw lthread 37 whosepitch is equal to the pitch of the spirals of part 20. Helico-spiral 21is moved axially due to the rotation of screw 37 A(upon which it -ismounted as a-nut) and is also 'moved axially -due to its own rotation onthel screw. Now, if ythe :idle wheel 22 is carried toward the 'left soas to keep in mesh with the spiral 2O the helico-spiral 21 willv movethe appropriate amount to keep in mesh with the idle wheel.

In Fig. y5 is shown a side view of the support for the idle wheel 22 sodesigned as to move this idle wheel axially so as to maintain meshing.Its spindle is mounted on yav frame 41 suitably guided so as to `.beincapable of rotation about the axis .of a rod 42 upon which it canfreely slide. Rod 42 is Vfixed to a nut upon screw lel to and behindshaft 10 but not shown in Fig. 4. A wheel 44 ygears with wheel 33 sothat as the member 2O is lrotated 33 drives 44 and rotates 43 therebytranslating lthe frame 41, perpendicular to the paper `in Fig. 5 andparallel to the paper in Fig. 4, the pitch of the screw "43 andthe'ra'tio of the gearing 33, 35 being ysuitably chosen to cause 22 toremain in continuous mesh with .the two helico-spirals'20 and 21.' Thiscondition is satisfied by the screw 43 being geared to the helico-spiral2O by gearing in theinverse ratio of .the pitches of the screw 43 and.member `20, while rotation is imparted to the screwed sh aft 36proportional to the rotation of the helico-spiral 2O in such 43 placedparal a way that the axial translation of the member 21, due to therotation of the screw 36, is proportional to the angular rotation of themember 20, while the member'21has also an axial translation proportionalto kits own'rotation on theV shaft 36, on which it is threaded as a nut.t

Inasmuchl Ias the helico-spiral 21 goes axial displacement in theoperation of `the apparatus and wheel 14 and member 21 mentioned thatthe luniform scale portion of the mechanism is geared to bevel wheel 3junder- Y so that one revolution of the handle 5 does not correspond tothe same change in range at all parts of thetravel. The mechanism could,however, be designed so that the unin form scale portion of themechanism Was geared directly to handle 5.

1n the above We have described the application of our invention to aproblem met With in connection with rangefinders Where it is desired toconvert motion according to a reciprocal scale of ranges into motionaccording to a uniform scale. This is done only by way of illustrationand We do not confine ourselves to this particular application of theinvention which may be used in other cases for the conversion of motionsWithin limits as to the extent of these motions, z'. e., it is not amechanism Which can convey motion from one shaft to anothercontinuously.

We claim: y

1. Apparatus comprising three gear elements constituting a maindifferential gear, means for applying to the first and second elementsforces tending to drive them in opposite senses so far as their effectson the third element are concerned,.associated with mechanism forcontrolling the ratio of the motions imparted to the first and secondelements in a predetermined progressively varying manner, for thepurposes set forth.

2. Apparatus comprising three gear elements constituting a maindifferential gear, and three gear elements constituting a supplementarydifferential gear, the first and second elements of the supplementarygear being in driving connection with the first and second elements ofthe main gear respectively, means for imparting motion to the thirdelement of the supplementary gear, the said driving connection beingsuch that forces are transmitted to the first and second elements of thesupplementary gear Ytending to drive the first and second elements ofthe main gear in opposite senses so far as their effects on the thirdelement of the main gear are concerned, associated with mechanism forcontrolling the ratio of the motions imparted to the first and secondelements of the main gear in a varying manner, for the purposes setforth.

3. Apparatus comprising three gear elements constituting a maindifferential gear, means for applying to the first and second elementsforces tending to drive them in opposite senses so far as their effectson the third elementare concerned, associated With mechanism forcontrolling the ratio of the motions imparted to the first and secondelements in a `varying manner so that the motion of one of the first andsecond elements is inaccordance with the lavv of motion A to beconverted and thatofthe third element is in accordance with the laW ofmotion'B desired, substantially as set forth.

t. Apparatus comprising three gear elements constituting a maindifferential gear, and three gear elements constituting a supplementarydifferential gear, the first and second elements of the supplementarygear being in driving connection With the first and second elements `ofthe main gear respectively, means for imparting motion to the thirdelement of the supplementary gear, the said driving connection beingsuch that forces are transmitted to the first and second elements of thesupplementary gear tending to drive the first and second Velements ofthe main gear in opposite senses sol far as their effects on bthe'thirdelement of the main gear are concerned, associated with mechanism forcontrolling the ratio of the motions imparted to the first and secondelements of the main gear in a varying manner so that the motion of oneof the elements of the supplementary gear is in 4accordance With thelavv of motion A to be convertedV and that of the third element' of themain gear is in accordance with the law of motion B' desired.

5. Apparatus comprising three gear elements constituting a maindifferential gear, means for applying to thefirst and second elementsforces tending to drive them in opposite senses so far as their effectson Vthe third element are concerned, associated with mechanismcomprising toothed-spiral mem-V bers for controlling the ratio of themotions imparted to the first and second elements in a varying manner,for the purposes set forth.

6. Apparatus comprising threegear elements constituting a maindifferential gear, means for applying to the first and second elementsforces tending to drive them in opposite senses so far as their effectson the third element are concerned, associated with mechanism comprisingtivo toothed helicof spiral members, associated With means for impartingaXial translation to one of the members and for imparting rotationalmotion to each, for controlling the ratio of the motions imparted to thefirst and second ele'- ments in a varying manner,for the purposes setforth.

7. Apparatus comprisingV three gear elements constituting a maindifferential gear, and three gear elements constituting a supplementarydifferential gear, the ,first and second elements of the supplementarygear being in driving connection with the.y first and second elementsofthe main gear respectively, means for imparting motion to the thirdelement of the supplementary gear, the said driving connection beingsuch that forces are transmitted to the first and second elements of thesupplementary gear tending to drive the` first and second elements ofthe main gear in opposite senses so far as their effects on the thirdelement ofthe maingear are concerned, associated With mechanismcomprising toothed spiral members for controlling the ratio of themotions imparted to the first and second elements of the main gear in avarying manner, for the purposes set forth.

8. Apparatus comprising three gear ele# ments constituting a maindifferential gear, and three gear elements constituting a supplementarydifferential gear, the first and second elements of the supplementarygear being in driving connection With the first and second elements ofthe main gear respectively7 means for imparting motion to the thirdelement of the supplementary gear, the said driving connection beingsuch that forces are transmitted to the first and second elements of thesupplementary gear tending to drive the first and second elements of themain gear in opposite senses so far as their effects on the thirdelement of the main gear are concerned, associated with mechanismcomprising two toothed helico-spiral members, associated With means forimparting axial translation to one of the members and for impartingrotational motion to each for controlling the ratio of the motionsimparted to the first and second elements of the main gear in a varyingmanner, for the purposes set forth.

9. Apparatus comprising three gear elements constituting a maindifferential gear, means for applying to the first and second elementsforces tending to drive them in opposite senses so far as their effectson the third element (the jockey) are concerned, associated Withmechanism for controlling the ratio of the motions imparted to the firstand second elements in a predetermined progressively varying manner, forthe purposes set forth.

10. Apparatus comprising three gear elements constituting a maindifferential gear, and three gear elements constituting a supplementarydifferential gear, the first and second elements of the supplementarygear being in driving connection with the first and second elements ofthe main gear re spectively, means for imparting motion to the thirdelement (thejockey) of the supplementary gear, the said drivingconnection being such that forces are transmitted to the first andsecond elements of the supplemen` tary gear tending to drive the firstand second elements of the main gear in opposite senses so far as theireffects on the third element (the jockey) of the main gear areconcerned, associated with mechanism for controlling the ratio of themotions imparted to the first and second elements of the main gear in avarying manner, for the purposes set forth.

`ARCHIBALD BARR. WVILLIAM STROUD.

Witnesses J Aims WEIR FRENCH, FRANCIS MORRISON. y

